Messages in this thread Patch in this message | | | From | Pankaj Gupta <> | Subject | [RFC v2 1/2] virtio-pmem: Async virtio-pmem flush | Date | Mon, 26 Jul 2021 08:08:54 +0200 |
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From: Pankaj Gupta <pankaj.gupta@ionos.com>
Implement asynchronous flush for virtio pmem using work queue to solve the preflush ordering issue. Also, coalesce the flush requests when a flush is already in process.
Signed-off-by: Pankaj Gupta <pankaj.gupta@ionos.com> --- drivers/nvdimm/nd_virtio.c | 72 ++++++++++++++++++++++++++++-------- drivers/nvdimm/virtio_pmem.c | 10 ++++- drivers/nvdimm/virtio_pmem.h | 14 +++++++ 3 files changed, 79 insertions(+), 17 deletions(-)
diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c index 10351d5b49fa..61b655b583be 100644 --- a/drivers/nvdimm/nd_virtio.c +++ b/drivers/nvdimm/nd_virtio.c @@ -97,29 +97,69 @@ static int virtio_pmem_flush(struct nd_region *nd_region) return err; }; +static void submit_async_flush(struct work_struct *ws); + /* The asynchronous flush callback function */ int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) { - /* - * Create child bio for asynchronous flush and chain with - * parent bio. Otherwise directly call nd_region flush. + /* queue asynchronous flush and coalesce the flush requests */ + struct virtio_device *vdev = nd_region->provider_data; + struct virtio_pmem *vpmem = vdev->priv; + ktime_t req_start = ktime_get_boottime(); + + spin_lock_irq(&vpmem->lock); + /* flush requests wait until ongoing flush completes, + * hence coalescing all the pending requests. */ - if (bio && bio->bi_iter.bi_sector != -1) { - struct bio *child = bio_alloc(GFP_ATOMIC, 0); - - if (!child) - return -ENOMEM; - bio_copy_dev(child, bio); - child->bi_opf = REQ_PREFLUSH; - child->bi_iter.bi_sector = -1; - bio_chain(child, bio); - submit_bio(child); - return 0; + wait_event_lock_irq(vpmem->sb_wait, + !vpmem->flush_bio || + ktime_before(req_start, vpmem->prev_flush_start), + vpmem->lock); + /* new request after previous flush is completed */ + if (ktime_after(req_start, vpmem->prev_flush_start)) { + WARN_ON(vpmem->flush_bio); + vpmem->flush_bio = bio; + bio = NULL; + } + spin_unlock_irq(&vpmem->lock); + + if (!bio) { + INIT_WORK(&vpmem->flush_work, submit_async_flush); + queue_work(vpmem->pmem_wq, &vpmem->flush_work); + return 1; + } + + /* flush completed in other context while we waited */ + if (bio && (bio->bi_opf & REQ_PREFLUSH)) { + bio->bi_opf &= ~REQ_PREFLUSH; + submit_bio(bio); + } else if (bio && (bio->bi_opf & REQ_FUA)) { + bio->bi_opf &= ~REQ_FUA; + bio_endio(bio); } - if (virtio_pmem_flush(nd_region)) - return -EIO; return 0; }; EXPORT_SYMBOL_GPL(async_pmem_flush); + +static void submit_async_flush(struct work_struct *ws) +{ + struct virtio_pmem *vpmem = container_of(ws, struct virtio_pmem, flush_work); + struct bio *bio = vpmem->flush_bio; + + vpmem->start_flush = ktime_get_boottime(); + bio->bi_status = errno_to_blk_status(virtio_pmem_flush(vpmem->nd_region)); + vpmem->prev_flush_start = vpmem->start_flush; + vpmem->flush_bio = NULL; + wake_up(&vpmem->sb_wait); + + /* Submit parent bio only for PREFLUSH */ + if (bio && (bio->bi_opf & REQ_PREFLUSH)) { + bio->bi_opf &= ~REQ_PREFLUSH; + submit_bio(bio); + } else if (bio && (bio->bi_opf & REQ_FUA)) { + bio->bi_opf &= ~REQ_FUA; + bio_endio(bio); + } +} MODULE_LICENSE("GPL"); diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c index 726c7354d465..56780a6140c7 100644 --- a/drivers/nvdimm/virtio_pmem.c +++ b/drivers/nvdimm/virtio_pmem.c @@ -24,6 +24,7 @@ static int init_vq(struct virtio_pmem *vpmem) return PTR_ERR(vpmem->req_vq); spin_lock_init(&vpmem->pmem_lock); + spin_lock_init(&vpmem->lock); INIT_LIST_HEAD(&vpmem->req_list); return 0; @@ -57,7 +58,12 @@ static int virtio_pmem_probe(struct virtio_device *vdev) dev_err(&vdev->dev, "failed to initialize virtio pmem vq's\n"); goto out_err; } - + vpmem->pmem_wq = alloc_workqueue("vpmem_wq", WQ_MEM_RECLAIM, 0); + if (!vpmem->pmem_wq) { + err = -ENOMEM; + goto out_err; + } + init_waitqueue_head(&vpmem->sb_wait); virtio_cread_le(vpmem->vdev, struct virtio_pmem_config, start, &vpmem->start); virtio_cread_le(vpmem->vdev, struct virtio_pmem_config, @@ -90,10 +96,12 @@ static int virtio_pmem_probe(struct virtio_device *vdev) goto out_nd; } nd_region->provider_data = dev_to_virtio(nd_region->dev.parent->parent); + vpmem->nd_region = nd_region; return 0; out_nd: nvdimm_bus_unregister(vpmem->nvdimm_bus); out_vq: + destroy_workqueue(vpmem->pmem_wq); vdev->config->del_vqs(vdev); out_err: return err; diff --git a/drivers/nvdimm/virtio_pmem.h b/drivers/nvdimm/virtio_pmem.h index 0dddefe594c4..d9abc8d052b6 100644 --- a/drivers/nvdimm/virtio_pmem.h +++ b/drivers/nvdimm/virtio_pmem.h @@ -35,9 +35,23 @@ struct virtio_pmem { /* Virtio pmem request queue */ struct virtqueue *req_vq; + struct bio *flush_bio; + /* last_flush is when the last completed flush was started */ + ktime_t prev_flush_start, start_flush; + + /* work queue for deferred flush */ + struct work_struct flush_work; + struct workqueue_struct *pmem_wq; + + /* Synchronize flush wait queue data */ + spinlock_t lock; + /* for waiting for previous flush to complete */ + wait_queue_head_t sb_wait; + /* nvdimm bus registers virtio pmem device */ struct nvdimm_bus *nvdimm_bus; struct nvdimm_bus_descriptor nd_desc; + struct nd_region *nd_region; /* List to store deferred work if virtqueue is full */ struct list_head req_list; -- 2.25.1
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